1. Field of the Invention
This invention relates to high performance multiconductor flat cable and more particularly to controlled impedance low loss low attenuation cable employing a plurality of conductor pairs which can be used in undercarpet installations.
2. Description of the Prior Art
Conventional multiconductor cable for transmitting high frequency digital signals includes both shielded twisted pair cable and coaxial cable. Shielded twisted pair cable utilizes a conventional twisted pair configuration and employs a shield around the twisted pair to reduce EMI radiation and to minimize cross talk. Coaxial cables similarly use an EMI shield to reduce radiation and cross talk.
Considerable effort has been extended to develop a flat multiconductor coaxial cable which would yield the same performance as conventional coaxial cable but would also enable the use of conventional mass termination techniques to attach connectors to the cable. For example, U.S. Pat. No. 4,488,125 discloses a flat cable assembly in which a signal conductor and at least one drain conductor are embedded in a first insulating matrix and surrounded by a shield which is in turn surrounded by an outer insulating layer. The drain wires are positioned in contact with the outer layer to enable both the signal and drain wires to be connected by a mass termination process. Other flat coaxial cables are disclosed in U.S. Pat. Nos. 4,487,992 and 3,775,552. One application for flat data cable is the use of this cable in under the carpet wiring situations in which a flat low profile cable is extended beneath a carpet for connection to digital equipment.
Conventional twisted pair cable does not have a profile suited for use in undercarpet applications. The invention disclosed herein comprises a relatively low profile flat cable having the performance characteristics of shielded twisted pair cable but yet having a low profile suited for undercarpet installations. The flat cable disclosed herein also has the mass termination capabilities of flat cable with conductors spaced on repeatable precise center lines, unlike conventional shielded pair cable.